Synchronous electrical contact-maker.



F. G. COTTRELL & H. A. BURNS. svwcnaowous ELECTRICAL comm MAKER.

APPLICATION FILED SEPT- 9. 1909. 1,143,175, Patented June 15, 1915.

2 SHEETSSHEET 1.

F. G. COTTRELL & H. A. BURNS. SYNCHRONOUS ELECTRICAL CONTACT MAKER.

APPL1CATION FILED SEPT.911909.

Patented June 15, 1915.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

FREDERICK GARDNER COTTRELL, OF BERKELEY, AND HERBERT ALEXANDER-BURNS,

OF OAKLAND, CALIFORNIA, ASSIGNORS "T0 INTERNATIONAL IPRECIIEITATION COM-?ANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

SYNCHRONOUS ELECTRICAL CONTACT-MAKER.

Specification of Letters Patent.

Patented June 15, 1915.

Application filed September 9, 1909. Serial No. 516,950.

To all whom it may concern:

Be it known that we, FREDERICK GARDNER CoT'rRELL and HERBERT ALEXANDERBURNs, citizens of the United States, residing the said COTTRELL atBerkeley, in the county of Alameda and State of California, and the saidBURNS at Oakland, Alameda. county, California, have invented certain newand useful Improvements in Synchronous Electrical Contact-Makers, ofwhich the following is a specification.

Our invention relates to electrical contact makers; and it has for itsobject the provision of a simple and effective apparatus forintermittently connzting systems of conductors with a high potentialalternating current circuit at intervals synchronized with the period ofthe same in such wise as to maintain constant polarity in theseconduotors.

To this end our invention consists in the novel construction andarrangement of the apparatus, which we shall hereinafter fully describe,by reference to the accompanying drawings in Which Figure 1 is aperspective view of our contact maker. Fig. 2 is an end View of thesame. Fig. 3 is a side View of the same. Fig. 1 is a front View of oneof the contactor elements. Fig. 5 is a section of the same. Fig. 6 is afront View of one of the brush holders and brushes. Fig. 7 is a sideview of the same. Fig. 8 is a plan of the brush.

The type of contact maker here illustrated is one-designed for a singlephase circuit,

and is here shown as operated by a four pole V synchronous motor, but itis to be understood that our invention equally applies to multiphasecircuits and other multipolar synchronous motors or other means fordriving it.

1 is a base from which rises a frame 2, whose structure includes, inthis instance, four equidistant, radiating arms 3, at each end. In thesearms are carried four brushbearers 4:, each being made of insulatingmaterial sufiiciently rigid and strong, say, for example, miconite,preferably, of tubular section. Each bearer 4 is adjustably fitted toits arms 3, in any suitable manner to enable it to be moved to andadjusted in its proper positionin a radial plane' For example, the endsof each bearer may have embedded in them short bolts 5 which passthrough slots 6 in the arms, and receive clamping nuts 7 on their outerends. Upon each brush-bearer 4:, are mounted two brushes, making eightin the system. These are in corresponding positions and are adjustablymounted. For clearness of descript1on hereafter, these brushes are thusdesignated, to wit :-A and Bon one bearer; C and D on the bearerdiametrically opposite; E and F on the bearer between these on one side,and G and H on the bearer on the opposite side. The details of mountingthese brushes are the same in all, and a description of one, say, A, byreference to Figs. 6, 7 and 8 will suflice.

The brush-holder as shown in Figs. 6 and 7 comprises a sectionalmetallic ring 8 fitted upon the bearer 4. One section of this ringcarries a squared projection 9, between the face of which and achanneled cap plate 10, the brush A is clamped by screws 11. The brush Ais best slitted as shown at a, in Fig. 8, so that it may slip over andbe guided by the screws 11 in its adjustment relatively to its holder.The sections of the holder ring are clamped together by a bolt and thumbnut. at 12.

It will now be seen that there are four ways of changing the brushadjustment. First, by moving the bearers 4 radially. Second, by rotatingthe brush holders on the bearers. Third, by sliding said holderlengthwise on the bearers. Fourth, by moving the brushes forward or backin their holders. The brush-holders are thus insulated fromone anotherand from the frame.

Mounted to rotate in the frame 2, is a shaft 13 which lies in the axisfrom which the arms 3 of the frame radiate. This shaft carriesv thecontactors of which there are two, designated as a whole by I and J. Asthey are alike in construction, a description of one, by reference toFigs. 4 and 5 will answer for both.

The shaft 13 between its end bearings, is covered with an insulatingtube 14 of some suitable material, such as hard rubber, micanite,micabestos, etc., which tube fits the shaft snugly. Upon this tube isfitted a hub sleeve 15 one end of which is split and taper-threaded toreceive a nut 16 which clamps the sleeve to the tube in a manner whichminimizes the weakening of the insulation through injury. The sleeve 15is formed with or carries a collar 17, to which is screwed a disk 18 ofinsulating material, such as rubber, or micanite or micabestos or othersuitable substance. To the outer portion of this disk 18 is fitted andsecured a metallic ring 19, from which extend the diametrically oppositeprojections 20. The number of these projections depends upon the numberof phasesfrom which the current is to be drawn, being two for thephasetype herein illustrated, separated by 180 de-' grees. To the outerend of each projection 20 is removably fitted a rod 21 of smalldiameter, a good way of fitting said rod being here indicated, namelyslipping the rod into a hole drilled radially through the thickened endof the projection, the inner end of the rod being riveted or headed upto prevent it from being thrown out by centrifugal force. The purpose ofthe insulating disk 18 is to safeguard against electric puncture of theinsulating tube 14.

The relation of the contactors to the brushes is such that contactor lloperates electrically with brushes A, C, E and G, and contactor Joperates with brushes B, D, F and H. The contactors are relativelydisposed to each other in such wise that the rods 21 of one point in adirection 90 degrees from those of the other.

The projections 20 and rods 21 form con ductors extending outwardly fromthe ring to within sufficient proximity to the brushes to receivecurrent therefrom or deliver current thereto, at the high potentialsused with this apparatus, Without, however necessarily making actualcontact, (see Fig. 1) the potential being sufficiently high to jump thegap between such conductors and the brushes. This connection is however,only made intermittently, so that each conductor receives current fromthe brushes only during a portion of each cycle or half cycle of thealternating current and means, hereinafter described, are provided forrotating the contactors in synchronism with the alternating current, andfor shifting the phase position of the time of connection with relationto the alternating current, so as to take 0H current at any desiredpotential, up to the maximum of the alternating supply circuit. Theangular adjustment of the brush holders in the brush bearers enexample,by connecting it to the generator for the line itself, or to asynchronous motor driven from the system, the latter type being thatherein specifically represented and de scribed.

Secured to the base 1 is a cradle-stand 22 in which is seatedconcentrically an annular cradle-ring 23 to which the four polesynchronous motor 24 is securely fastened in such wise that its armatureshaft 13 is alined with the contactor carrier-shaft 13 to which it iscoupled suitably, or said shafts may be integral if desired.

The cradle-stand 22 has a slot 25, through which a handle 26 plays, saidhandle being fastened to the cradle ring 23, whereby the cradle ring maybe turned on its aXis in its seat in the stand. The stand is clamped onthe ring to hold it securely, by means of a bolt 27 at its top.

In action, the principal electrical features are as follows :Brushe's Aand G are electrically connected together by wire 28 and to one side 29of the high tension alternating current line. Brushes B and H areelectrically connected together by wire 30, and to the other side 31 ofthe high tension alternating current line. Brushes F and E areelectrically connected together by wire 32, and are connected by thewire 33 to one side of the load. Brushes D and C are electricallyconnected together by wire 34 and to the other side of the load throughthe ground by wire 35. t

36 indicates the low tension circuit to drive the motor. The brushes areso adjusted. that the rods 21 of contactor I connect electricallybrushes A and C at the same moment that the rods 21 of contactor Jconnect electrically brushes F and H; and similarly, upon rotation ofthe contactors through an angle of 90 degrees, brushes E and G areconnected simultaneously with the the connection of brushes B and D.

As heretofore stated, the synchronous motor 24 is a four-pole type;hence, it revolves once during every two complete cycles of thealternating current by which it is driven. The high tension alternatingcurrent circuit source must be synchronized with the low tension circuitdriving the motor, the one being most conveniently transformed from theother,'as indicated by the transformer 37.

For convenience of description, beginning when brushes A and C areelectrically connected, at which moment brushes F and H are also soconnected, let it be assumed that the potential difference between theterminals at brushes A and B is a maximum; then A is connected throughI, C and 35 to the ground to one side of the load which is alsogrounded; while, simultaneously, B is connected through H, J, F and E tothe insulated side of the load. By the rotation of the shaft, thecircuitis then opened simultaneously at four points in series, namely,at

A, o, H and F. After a half, cycle of the alternating current circuit,at which time the potential difference between terminals A and B isagain a maximum, but in an op-" posite sense, the armature of the motorbeing four-poled, will have rotated one-quarter of its revolution, thusbringing B into,

contact with the grounded side of the load through J, D, C and 35, andat the same time connecting A to the insulated side of the load throu hG, I and E. At the end of the next half cycle the previous connectionsare restored. This process is repeated every half revolution of theshaft system, and thus with every complete cycle of the alternatingcurrent circuit.

Now, in order that the connection of A and B through the contactors tothe load may be made at the instant that the potential differencebetween A and B is a maximunnbr is any desired per cent. of the maximum,the feature, heretofore described, of the bodily adjustment of the motoron its axis by the turning of the cradle ring 23 in its seatis'proyided. By thus bodily turning the motor, the time of contact ofthe contactors l and J withthe brushes may be so adjusted that thepotential difierence at A and B may be impressed upon the load at any ofits valueslhe several types of insulation heretofore described are forthe satisfactory operation of an apparatus of this nature, where highpotential diiierences exist between its parts. Since when the contactorsl and J make electrical connection with the brushes A and B, the samepotential difference exists between the contactors themselves as betweensaid terminals A and B; and, also, since between each contactor and baseframe this same difference of potential is alternately established, theinsulation surface of the tube 14 between the contactor-hub-sleeves 15and between these and the bearing frame must be of sufficient length tolimit the electric surface leakage to a negligible amount. Having thusdescribed our invention what -we claim asnew and desire to secure byLetters Patent is 1. An apparatus for maintaining a system of conductorsat a high difference of electrical potential by intermittent connectionwith a source of alternating current at intervals synchronized with theperiodof the current, comprising a system of eight brushes in twoseparated annular series, each series having four equidistant brushesand each brush ofone series being aline with a corresponding brush ofthe other series in a line parallel with the axis of the system, twoadjacent brushes of one annular series being connected th one side ofthe alternating circuit,'and two adjacent brushes of the other annularseries being connected to the other side of the alternatmg currentcircuit and the other two brushes of each annular series being connectedrespectively to opposite sides of the system of conductors contact withthe brushes of one of the annular series of brushes and the other pairof said conductors being adapted to contact with the brushes of theother annular series of brushes, whereby said conductors by theirrotation alternately become connecting links between pairs of saidbrushes and are sep arated entirely therefrom, thus opening the circuitsimultaneously at four points in series. a

2. An, apparatus for maintaining a system of conductors at a highdifierence of electrical potential by intermittent connection with asource of alternating current at intervals synchronized with the periodor" the current, comprising a shaft driven in synchronism with thealternating current; a system of eight brushes in two separated annularseries, each series having four equidistant brushes, and each brush ofone series being alined with a corresponding brush of the other seriesin a line parallel with the axis of the system, two adjacent brushes ofone annular series being connected to one side of the alternatingcircuit, and two adjacent brushes of the other annular series beingconnected to the other side of the alternating current circuit and theother two brushes of each annular series being connected respectively toopposite sides of the system of conductors to be char ed to highpotential; and a series of conducting elements includingd-our'projecting conductors carried by said shaft, said conductors being inseparated pairs, insulated from each other, the conductors of each pairbeing diametrically opposite, and those of one pair being set quarteringto those of the other pair, one pair of said conductors being adapted tocontact with the brushes of'one of the annular series of brushes and theother pair of said conductors being adapted to contact with the brushesof the other annular series of brushes, whereby said conductors by therotation of the shaft, alternately become connecting links between airsof said brushes and are separated there rom, thus opening the circuitsimultaneously at four points in series.

3. An apparatus for maintaining a sys tern of conductors at a highdifference of electrical potential by intermittent connection withasource of alternating current at intervals synchronized with the periodof the current, comprising a synchronous .mo-'

tor; a shaft driven by and. in unison with the motor shaft a system ofeight bi ushes in two separated annular series, each series having fourequidistant'brushes, and each brush of one series being alined with a"corresponding brush of the other series in a line parallel with the axisof the system, two adjacent] brushes of one annular series beingconnected to one side of the alternating circuit, and two adjacentbrushes of the other annular series being connected to the other side ofthe alternating current circuit and the other two brushes of eachannular series being connected respectively to opposite sides of thesystem of conductors to be charged to high potential; and a series ofconducting elements including four projecting conductors carried by saiddriven shaft, said conductors being in separated pairs, insulated fromeach other, the conductors of each pair being diametrically opposite,and those of one pair being set quartering to those of the other pair,one pair of said conductors being adapted to contact with the brushes ofone of the annular series of brushes and the other pair of saidconductors being adapted to contact with the brushes of the otherannular series of brushes, whereby said conductors by the rotation ofthe shaft, alternately become connecting links between pairs of saidbrushes and are separated therefrom, thus opening the circuitsimultaneously at four points in series.

4:. An apparatus for maintaining a system of conductors at ahighdifference. of electrical potential by intermittent connection with asource of alternating current at intervals synchronized with the periodof the current, comprising a synchronous motor having a shaft; acradle-ring in which said motor is secured; a cradle-stand in which thecradle-ring is concentrically mounted and in which it is adapted to beangularly adjusted with respect thereto, whereby said motor is capableof a rotary adjustment about the axis of its own shaft; a shaft drivenby and 'in unison with the motor shaft; a system of eight brushes in twoseparated annular series, each series having fe ur equidistant brushes,and each brush of one series being alined with a corresponding brush ofthe other series in a line parallel with the axis of the system, saidbrushes being connected respectively to the alternating current circuitand to the system of conductors to be charged to high potential; and aseries of conducting elements including four projecting conductorscarried by said driven shaft, said conductors being in separated pairsinsulated from each other, the conductors of each pair beingdiametrically opposite, and those of one pair being set quartering tothose of the other pair, one pair of said conductors being inear/tadapted to contact with the brushes of one of the annular series ofbrushes and the other pair of said conductors being adapted to contactwith the brushes of the other annular series of brushes, whereby saidconductors by the rotation of the shaft, alternately become connectinglinks between pairs of said brushes and are separatedtransformer andmechanically connected to said rotary member, to rotate the latter insynchronism with the alternating supply current, and the stator of saidmachine being shiftable around the axis of rotation of the rotor, toselect the 'part of the wave at which connection is established, andthereby variably control the electromotive force impressed on thedelivery connections.

6, A rectifying apparatus comprising supply and delivery conductorsarranged in circular series, a stepup transformer provided. withalternating current supply connections and having its secondaryconnected to said supply conductors to impress alternating electromotiveforce waves thereon, a rotary member havlng conducting means cooperatingwith said conductors to intermittently establish connection between thesupply and delivery conductors, a synchronous motor having its armatureelectrically connected to the primary of said transformer andmechanically connected to said rotary member to rotate the latter insynchronism with the alternating supply current, the field magnet ofsaid machine being shiftable around the axis of rotation of thearmature, to selectthe part of the wave at which connection isestablished and thereby variably control the electromotive forceimpressed on the delivery connections.

7. In a rectifier, a rotary member comprising a rotating shaft,air-insulating disk carried by said shaft, a metal ring extending aroundand secured to, the periphery of said disk, and metallic conductorsconnected to and extending outwardly from said ring.

8. In a rectifier, a rotary shaft, insulated rotary conductors carriedbysaid shaft, a frame having guides extending radially with respect tosaid shaft, insulating supports adjustably mounted in 7. said guides,

and. brushes carried by said insulating supports and adapted tocooperate with said rotary conductors.

9. In an apparatus of the described character, a frame; a shaft mountedin the frame and driven in synchronism with the alternating current; aplurality of conducting elements including projecting conductors,carried by said shaft and insulated therefrom; an annular series ofbrush bearers'of insulating material carried by and radially adjustablein said frame; a series of brush holders mounted on the bearers andadjustable thereon rotatively; brushes with which the projectingconductors effect electrical connection, said brushes being carried byand adjustable in said holders, and being so placed with respect to therotating conducting elements that during a portion of each cycle all ofsaid brushes are out of connecting relations with said elements; andelectrical connections from the brush holders to the alternating currentcircuit and to the system of conductors to be charged to high potential.

10. in an apparatus of the described char acter and combination with asynchronous motor having a shaft; a cradlering' in vwhich said motor issecured; a cradle-stand in which the cradle ring is concentricallymounted and is adapted to be angularly adjusted with respect theretowhereby said motor is capable of a rotary adjustment about the axis ofits own shaft;

a frame; a shaft mounted in the frame and driven by and in unison withthe motor shaft; a plurality of conducting elements includingprojecting" conductors, carried by said driven shaft and insulatedtherefrom; an annular series of brush bearers of insulating materialcarried by and radially adjustable in saidframe; a series of brushholders mounted on the bearers and adjustable thereon rotatively;brushes with which the projecting conductors effect electricalconnection, said brushes being carried by and adjustable in saidholders; and electrical connections from the brush holders to thealternating current circuit and to the system of conductors to becharged to high potential.

11. In a rectifier a rotary shaft-an insulating tube surrounding saidshaft, a hubsleeve fitting on said insulatingtube and having one endportion split and tapered, a member surrounding and engaging saidtapered portion of the hub-sleeve, to clamp the hub-sleeve on theinsulating tube and circuit controlling conductors carried by saidl1ub-sleeve.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses FREDERICK GARDNER QOTTRELL.HERBERT ALEXANDER BURESQ Witnesses: WM. F, Boori-I,

D. B. RICHARDS.

